GNOME 2.2 Desktop on Linux System Administration Guide

Configuring GDM

To configure the GDM login screen, use the Login Screen Setup application. To open Login Screen Setup, choose Applications -> System Tools -> Login Screen Setup.


Note –

You must have system administrator or root access privileges to configure the GDM login screen.


You can configure GDM in the following functional areas:

General Settings

Use the General tabbed section to set general preferences for the GDM login screen.

Table 5–1 lists the general GDM settings that you can configure.

Table 5–1 General GDM Settings

Element 

Description 

Local

Select the type of interface to use for the login screen when users log in from a local system. Select one of the following options from the drop-down list: 

  • Graphical greeeter: Select this option to use a graphical login screen when users log in from a local system.

  • Standard greeeter: Select this option to use the standard GNOME login screen when users log in from a local system.

Remote

Select the type of interface to use for the login screen when users log in from a remote system. Select one of the following options from the drop-down list: 

  • Graphical greeeter: Select this option to use a graphical login screen when users log in from a remote system.

  • Standard greeeter: Select this option to use the standard GNOME login screen when users log in from a remote system.

Always use 24 hour clock format

Select this option to display the time on the login screen in the 00.00 to 24.00 format. 

Welcome string

Type a welcome message to display on the standard GNOME login screen when users log in from a local system. 


Note –

If you want to display the system name in the welcome message, type %n in this text box.


Remote welcome string

Type a welcome message to display on the standard GNOME login screen when users log in from a remote system. 

Login a user automatically on first bootup

Select this option to log in a user automatically when the user boots up the system for the first time. 

Automatic login username

Use the drop-down combination box to enter a username to use when the system logs in a user automatically. 

Login a user automatically after a specified number of seconds

Select this option to log in a user automatically after an interval that you specify. 

Timed login username

Use the drop-down combination box to enter a username to use when the system logs in a user automatically after an interval. 

Seconds before login

Use the spin box to specify how long to wait to log in the user automatically. 

Standard GNOME Login Screen Settings

Use the Standard greeter tabbed section to set preferences for the standard GNOME login screen.

Table 5–2 lists the standard GNOME login screen settings that you can configure.

Table 5–2 Standard GNOME Login Screen Settings

Element 

Description 

Logo

Choose an image to display as a logo on the standard GNOME login screen. To choose an image, enter the filename of the image in the drop-down combination box. Alternatively, click Browse to display a dialog from which you can choose an image.

Show choosable user images (face browser)

Select this option to display images of users on the standard GNOME login screen. If this option is selected, users can select an image instead of type a username. 

No background

Select this option if you do not want to display an image or color in the background of the standard GNOME login screen.  

Image

Select this option to display an image in the background of the standard GNOME login screen. To choose an image, enter the filename of the image in the drop-down combination box at the right side of the dialog. Alternatively, click on the Browse button at the right side of the dialog to display a dialog from which you can choose an image.

Color

Select this option to display a color in the background of the standard GNOME login screen. Use the Background color button to specify the color.

Scale background image to fit

If you select the Image option, select this option to scale the background image to fit the background of the standard GNOME login screen. The width-to-height ratio of the image is retained.

Only color on remote displays

Select this option to display a color in the background of the standard GNOME login screen when users log in from a remote system. 

Background color

If you select the Color option or the Only color on remote displays option for the background, use this button to specify the color. Click on the color selector button to display the color selector dialog. Choose the color that you require from the color selector dialog.

Graphical Login Screen Settings

Use the Graphical greeter tabbed section to set preferences for the graphical login screen.

Table 5–3 lists the graphical login screen settings that you can configure.

Table 5–3 Graphical Login Screen Settings

Element 

Description 

Theme list 

Select a theme to use for the graphical login screen. You can preview the theme at the right side of the dialog. 

Install new theme

You can add a theme to the list of available themes. The new theme must be an archive file that is tarred and zipped. That is, the new theme must be a .tar.gz file.

To install a new theme, perform the following steps: 

  1. Click on the Install new theme button.

  2. Use the dialog to select the archive file. When you have selected the file, click OK.

Delete theme

To delete a theme, select the theme, the click on the Delete theme button.

Security Settings

Use the Security tabbed section to set security preferences for GDM.

Table 5–4 lists the security settings that you can configure.

Table 5–4 Security Settings

Element 

Description 

Allow root to login with GDM

Select this option to enable users with system administrator or root access privileges to use GDM to log in from a local system.


Note –

Systems that support Pluggable Authentication Modules (PAM) ignore this option. The PAM libraries determine whether the user is on the local system.


Allow root to login remotely with GDM

Select this option to enable users with system administrator or root access privileges to use GDM to log in from a remote system.

Allow remote timed logins

Select this option to enable GDM to log in a user automatically after an interval, from a remote system.

Show actions menu

Select this option to enable users to use the Actions menu on the login screen.

Allow configuration from the login screen

Select this option to enable users to use the Configure the login manager item from the Actions menu on the login screen.

Allow running XDMCP chooser from the login screen

Select this option to enable users to use the Run XDMCP chooser item from the Actions menu on the login screen.

The Run XDMCP chooser item displays a list of hosts that can offer display management services. Users can choose a host to manage a session from this list.

Always disallow TCP connections to X server (disables all remote connections)

Select this option if you do not want users to be able to connect to the X Window System server from remote systems. 

Retry delay (seconds)

Use the spin box to specify how long to wait after a failed login attempt, to reactivate the Username field on the login screen.


Note –

Systems that support Pluggable Authentication Modules (PAM) ignore this option.


XDMCP Settings

Use the XDMCP tabbed section to set preferences for X Display Manager Control Protocol (XDMCP).

Table 5–5 lists the XDMCP settings that you can configure.

Table 5–5 XDMCP Settings

Element 

Description 

Enable XDMCP

Select this option to enable a remote X Windows System display to request an X Windows System session from the system. 

Honour indirect requests

Select this option to enable remote X Windows System displays that do not have a display manager to request XDMCP display management services from this system. 

Listen on UDP port

Use the spin box to specify the port number on which to listen for User Datagram Protocol (UDP) requests.

Maximum pending requests

Use the spin box to specify the maximum number of queued requests for sessions from the system. 


Note –

Use this option to help avoid denial of service attacks. This option specifies the number of displays that can request a session at one time. This option does not specify the total number of remote sessions which GDM allows.


Max pending indirect requests

GDM creates a queue of requests for sessions from the system. Use the spin box to specify the maximum number of queued requests for sessions from displays that do not have a display manager.

Maximum remote sessions

Use the spin box to specify the total number of remote sessions which GDM allows.

Maximum wait time

Use the spin box to specify how long to wait before GDM removes a request from the queued requests.

Maximum indirect wait time

Use the spin box to specify how long to wait before GDM removes displays that do not have a display manager, from the queue of displays that have requested sessions.

Displays per host

Use the spin box to specify the total number of sessions which GDM allows from a host.

Ping interval (minutes)

GDM pings sessions to check that the session is still active. Use the spin box to specify the interval between pings from GDM.